Air-conditioning system

ABSTRACT

An air-conditioning system includes a plurality of indoor units, an outdoor unit, a refrigerant pipe including a branch portion and being divided into a plurality of flow sections, a plurality of control valves, a plurality of pressure sensors, and a controller. The control valves include indoor-unit control valves, and a plurality of pipe control valves. The pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units. The pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves. The controller opens or closes the control valves, compares a pressure of refrigerant to a predetermined threshold, and detects refrigerant leaking in the flow section where a pressure of refrigerant measured is determined to be lower than the predetermined threshold.

TECHNICAL FIELD

The present disclosure relates to an air-conditioning system including a plurality of indoor units and an outdoor unit.

BACKGROUND ART

An air-conditioning system has hitherto been known which includes a plurality of indoor units installed on each floor of a budding or in a large room or other space. Such a related-art air-conditioning system as described above may be provided with a refrigerant leakage detection sensor that detects refrigerant leakage to ensure safety when refrigerant leakage occurs. Patent Literature 1 discloses an air-conditioning system including a plurality of indoor units and a plurality of refrigerant leakage detection sensors installed in a room, in which the indoor units are further provided with respective pressure sensors. In the air-conditioning system disclosed in Patent Literature 1, when the refrigerant leakage detection sensor detects refrigerant leaking in a room, the air-conditioning system controls the supply of refrigerant to prevent the refrigerant from being supplied to each of the indoor units. Then, the respective pressure sensors detect whether the pressure of refrigerant in their corresponding indoor units has decreased to an atmospheric pressure or to a pressure close to the atmospheric pressure. In Patent Literature 1, due to this operation, the air-conditioning system identifies an indoor unit in which refrigerant leakage has occurred, and continues running of the indoor units other than the identified indoor unit.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent No. 6428717

SUMMARY OF INVENTION Technical Problem

However, in the air-conditioning system disclosed in Patent Literature 1, the pressure sensors are provided in the corresponding indoor units. Due to this configuration, in the air-conditioning system in Patent Literature 1, the pressure sensors cannot locate a place where refrigerant leaks in a refrigerant pipe that connects the indoor units and an outdoor unit.

The present disclosure has been made to solve the above-mentioned problem, and an object of the present disclosure is to provide an air-conditioning system that locates a place where refrigerant leaks in a refrigerant pipe.

Solution to Problem

An air-conditioning system according to an embodiment of the present disclosure includes: a plurality of indoor units configured to condition air in a room; an outdoor unit configured to supply refrigerant to each of the indoor units; a refrigerant pipe including a branch portion from which the refrigerant pipe branches off in parallel for each of the indoor units, the refrigerant pipe connecting each of the indoor units and the outdoor unit through the branch portion, the refrigerant pipe being divided into a plurality of flow sections, the refrigerant pipe being a pipe through which refrigerant flows; a plurality of control valves provided in the refrigerant pipe such that the plurality of control valves are positioned at opposite ends of each of the flow sections, the plurality of control valves being configured to control a flow of refrigerant in the flow sections; a plurality of pressure sensors provided on the refrigerant pipe, and configured to measure a pressure of refrigerant flowing through the refrigerant pipe; and a controller connected to a plurality of the control valves, and configured to control a plurality of the control valves, wherein the control valves include indoor-unit control valves provided in a plurality of the indoor units, and a plurality of pipe control valves provided in the refrigerant pipe, wherein the pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units, the pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves, and the controller includes an opening-closing unit configured to open or close the control valves connected to the controller, a first comparison unit configured to compare a pressure of refrigerant to a predetermined threshold, the pressure of refrigerant being measured by each of the indoor-side pressure sensors, in a plurality of the flow sections where the control valves closed by the opening-closing unit are positioned at opposite ends, and a first detection unit configured to detect refrigerant leaking in the flow section where a pressure of refrigerant measured by each of the indoor-side pressure sensors is determined to be lower than the predetermined threshold by the first comparison unit.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, the controller compares the pressure of refrigerant measured by each of the indoor-side pressure sensors to a predetermined threshold in the flow section in which the indoor-unit control valve and the indoor-side pipe control valve are positioned at opposite ends. In general, when refrigerant leaks from a refrigerant pipe, the pressure of refrigerant flowing through the refrigerant pipe decreases. As described above, the controller according to an embodiment of the present disclosure compares the pressure of refrigerant measured by the indoor-side pressure sensor to the predetermined threshold. Due to this operation, the controller detects refrigerant leaking in the flow section where the pressure of refrigerant measured by the indoor-side pressure sensor is determined to be lower than the predetermined threshold. Therefore, the air-conditioning system can locate where refrigerant leaks in the refrigerant pipe.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram illustrating an air-conditioning system 1 according to Embodiment 1.

FIG. 2 is a circuit diagram illustrating a control box 5 a according to Embodiment 1.

FIG. 3 is a functional block diagram illustrating a controller 9 according to Embodiment 1.

FIG. 4 is a flowchart illustrating the operation of the controller 9 according to Embodiment 1.

FIG. 5 is a circuit diagram illustrating an air-conditioning system 101 according to Embodiment 2.

FIG. 6 is a functional block diagram illustrating a controller 109 according to Embodiment 2.

FIG. 7 is a circuit diagram illustrating an air-conditioning system 201 according to Embodiment 3.

DESCRIPTION OF EMBODIMENTS Embodiment 1

Embodiments of an air-conditioning system 1 will be described hereinafter with reference to the drawings. FIG. 1 is a circuit diagram illustrating the air-conditioning system 1 according to Embodiment 1. With reference to FIG. 1 , the air-conditioning system 1 will be described below. Note that in the descriptions below, suffixes “a,” “b,” and “c” are used. The suffixes are used to distinguish a plurality of identical components from each other. The identical components, which are denoted by the same reference numeral with different suffixes, are equivalent to each other. A component denoted by a reference numeral, but without a suffix, is represented as a collective term for a plurality of identical components. As illustrated in FIG. 1 , the air-conditioning system 1 includes indoor units 2, an outdoor unit 3, a refrigerant pipe 4, control boxes 5, control valves 6, refrigerant leakage detection sensors 7, pressure sensors 8, and controllers 9.

Indoor Unit 2

The air-conditioning system 1 includes two indoor units 2 a, two indoor units 2 b, and two indoor units 2 c. Note that while FIG. 1 illustrates six indoor units 2, the air-conditioning system 1 may include two to five indoor units 2, or may include seven or more indoor units 2. The indoor units 2 are configured to condition air in a room. Each of the indoor units 2 includes an indoor heat exchanger and an indoor fan (both of which are not illustrated). The indoor heat exchanger is configured to cause heat exchange to be performed between room air and refrigerant. The indoor heat exchanger functions as an evaporator during cooling operation, and functions as a condenser during heating operation. The indoor fan is a device to deliver room air to the indoor heat exchanger.

Outdoor Unit 3

The outdoor unit 3 is configured to supply refrigerant to each of the indoor units 2. Note that while FIG. 1 illustrates one outdoor unit 3, two or more outdoor units 3 may be provided. The outdoor unit 3 includes a compressor, a flow switching device, an outdoor heat exchanger, an outdoor fan, and an expansion unit (all of which are not illustrated). The compressor is configured to suck refrigerant in a low-temperature and low-pressure state, compress the sucked refrigerant into a high-temperature and high-pressure state, and discharge the compressed refrigerant. The flow switching device is configured to change the flow direction of refrigerant, and is, for example, a four-way valve. The outdoor heat exchanger is configured to cause heat exchange to be performed between refrigerant and outside air, and is, for example, a fin-and-tube heat exchanger. The outdoor heat exchanger functions as a condenser during cooling operation, and functions as an evaporator during heating operation. The outdoor fan is a device configured to deliver outside air to the outdoor heat exchanger. The expansion unit is a pressure reducing valve or an expansion valve to reduce the pressure of refrigerant and expand the refrigerant.

Refrigerant Pipe 4

The refrigerant pipe 4 is a pipe through which refrigerant flows. The refrigerant pipe 4 includes branch portions 11 from which the refrigerant pipe 4 branches off in parallel for each of the indoor units 2. The refrigerant pipe 4 connects each of the indoor units 2 and the outdoor unit 3 through the branch portions 11. The refrigerant pipe 4 branches off from the branch portions 11 to individual indoor units 2. A branch portion 11 a is connected in series to a branch portion 11 b and a branch portion 11 c. The refrigerant pipe 4 is divided into a plurality of flow sections. A flow section is a minimum unit for which a flow of refrigerant is controlled.

Note that the refrigerant pipe 4 may branch off from the branch portions 11 to individual groups of plural indoor units 2 such as on each floor of the building, Among the branch portions 11, the branch portion “b” and the branch portion “c” may be connected in parallel to the branch portion “a.” Further, a smaller number of branches may extend from the branch portions 11 toward the indoor units 2 than the number of branches extending from the branch portions 11 toward the outdoor unit 3. There may be one branch portion 11.

Control Box 5

FIG. 2 is a circuit diagram illustrating a control box 5 a according to Embodiment 1. The air-conditioning system 1 includes the control box 5 a, a control box 5 b, and a control box 5 c. As illustrated in FIG. 2 , the control box 5 a is a container in which the branch portion 11 a, a pipe control valve 13 a, and a controller 9 a are accommodated. The pipe control valve 13 a is included in the control valves 6 that will be described later. As illustrated in FIG. 1 , the control box 5 a is connected to a refrigerant leakage detection sensor 7 a and indoor-side pressure sensors 21 a by a communication line 31. The indoor-side pressure sensors 21 a are included in the pressure sensors 8 that will be described later. The control box 5 a is further connected to the indoor units 2 a by the communication line 31. The indoor units 2 a are connected to the branch portion 11 a, Note that the control box 5 a may have the indoor-side pressure sensors 21 a accommodated therein. Further, the air-conditioning system 1 may not necessarily include the control boxes 5.

Control Valve 6

The air-conditioning system 1 includes a plurality of control valves 6. The control valves 6 are configured to control a flow of refrigerant. The control valves 6 may be a solenoid valve that can linearly adjust the flow amount of refrigerant, or may be an opening-closing valve capable of solely being fully closed or fully opened. The control valves 6 are provided in the refrigerant pipe 4 such that the control valves 6 are positioned at opposite ends of each of the flow sections. The control valves 6 include indoor-unit control valves 12 a, indoor-unit control valves 12 b, and indoor-unit control valves 12 c, and also include the pipe control valve 13 a, a pipe control valve 13 b, and a pipe control valve 13 c.

Pipe control valves 13 are provided in the refrigerant pipe 4. As described above, the pipe control valve 13 a is accommodated in the control box 5 a, and connected to the controller 9 a by a communication line (not illustrated). The pipe control valve 13 a includes indoor-side pipe control valves 41 a and an outdoor-side pipe control valve 42 a. Note that a pipe control valve 13 b includes indoor-side pipe control valves 41 b and an outdoor-side pipe control valve 42 b. Further, a pipe control valve 13 c includes indoor-side pipe control valves 41 c and an outdoor-side pipe control valve 42 c, The indoor-side pipe control valves 41 a are provided between the branch portion 11 a and the indoor units 2 a. In addition, the indoor-side pipe control valve 41 a is provided between the branch portion 11 a and the indoor unit 2 b. Note that the indoor-side pipe control valves 41 a may only be provided between the branch portion 11 a and either of the indoor units 2 a, and between the branch portion 11 a and the indoor unit 2 b. The outdoor-side pipe control valve 42 a is provided between the branch portion 11 a and the outdoor unit 3. Note that the pipe control valves 13 may not necessarily include indoor-side pipe control valves 41 or outdoor-side pipe control valves 42. In this case, one pipe control valve 13 is provided at each branch point of the branch portions 11, and consequently the number of the pipe control valves 13 decreases.

Refrigerant Leakage Detection Sensor 7

The air-conditioning system 1 includes a refrigerant leakage detection sensor 7 a, a refrigerant leakage detection sensor 7 b, and a refrigerant leakage detection sensor 7 c. The refrigerant leakage detection sensors 7 are configured to detect refrigerant leakage from the refrigerant pipe 4. The refrigerant leakage detection sensor 7 a detects refrigerant leakage by targeting the refrigerant pipe 4 connected to the indoor units 2 a through the branch portion 11 a. The refrigerant leakage detection sensors 7 are installed indoors where a detection-target refrigerant pipe 4 is installed. Note that the air-conditioning system 1 may not necessarily include the refrigerant leakage detection sensors 7.

Pressure Sensor 8

The air-conditioning system 1 includes a pressure sensor 8 a, a pressure sensor 8 b, and a pressure sensor 8 c. The pressure sensors 8 are provided on the refrigerant pipe 4 to measure the pressure of refrigerant flowing through the refrigerant pipe 4. The pressure sensor 8 a includes a plurality of indoor-side pressure sensors 21 a. The pressure sensor 8 b includes a plurality of indoor-side pressure sensors 21 b. The pressure sensor 8 c includes a plurality of indoor-side pressure sensors 21 c. Each of the indoor-side pressure sensors 21 a is assigned with a sensor count. The sensor count refers to the number used for the controller 9 a to identify each of the indoor-side pressure sensors 21 a in turn. The indoor-side pressure sensors 21 a are provided between the indoor-unit control valves 12 a and the indoor-side pipe control valves 41 a. In addition, the indoor-side pressure sensor 21 a is provided between the indoor-unit control valve 12 b and the indoor-side pipe control valve 41 a.

Controller 9

The air-conditioning system 1 includes the controller 9 a, a controller 9 b, and a controller 9 c. As described above, the controller 9 a is connected to the pipe control valve 13 a by a communication line (not illustrated) to control the pipe control valve 13 a. The communication line 31 connected to the control box 5 a is connected to the controller 9 a. That is, the controller 9 a is connected to the refrigerant leakage detection sensor 7 a, the pressure sensor 8 a, and the indoor units 2 a through the communication line 31 to communicate with them. The controller 9 a communicates with the indoor units 2 a to control the indoor-unit control valves 12 a. Note that in a case where the indoor units 2 a include respective controllers (not illustrated) configured to control the indoor-unit control valves 12 a, the controller 9 a may control the indoor-unit control valves 12 a through the respective controllers included in the indoor units 2 a.

The controller 9 a is connected to the controller 9 b by the communication line 31. Note that the controller 9 b or the controller 9 c may be omitted. In this case, the controller 9 a may control the indoor-unit control valves 12 b and the pipe control valve 13 b instead of the controller 9 b controlling them, or the controller 9 a may control the indoor-unit control valves 12 c and the pipe control valve 13 c instead of the controller 9 c controlling them. Note that the controller 9 a may be accommodated in the indoor unit 2, the outdoor unit 3, or other device, or may be provided separately as an external unit.

Each of the controllers 9 includes dedicated hardware or a central processor (CPU, also referred to as “processor,” “computer,” “microprocessor,” “microcomputer,” or “processor”) configured to execute programs stored in a memory. When the controller 9 a is dedicated hardware, the controller 9 a is equivalent to, for example, a single circuit, a combined circuit, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. The functional units of the controller 9 may be individually implemented by separate units of hardware, or the functional units of the controller 9 may be implemented together by a single unit of hardware.

When the controller 9 is the CPU, the functions to be executed by the controller 9 are implemented by software, firmware, or a combination of the software and the firmware. The software and firmware are described as programs and stored in a memory (not illustrated). The CPU reads and executes the programs stored in the memory, thereby implementing the functions of the controller 9. For example, the memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM. Note that the functions of the controller 9 may be partially implemented by dedicated hardware, while being partially implemented by software or firmware.

FIG. 3 is a functional block diagram illustrating the controller 9 according to Embodiment 1. As illustrated in FIG. 3 , the controller 9 includes an opening-closing unit 32, a first comparison unit 33, and a first detection unit 34. The opening-closing unit 32, the first comparison unit 33, and the first detection unit 34 are made up of algorithms.

Opening-Dosing Unit 32

When the refrigerant leakage detection sensor 7 detects refrigerant leakage, the opening-closing unit 32 doses the control valves 6 connected to the controller 9. Note that the opening-dosing unit 32 may be configured to be started by a worker providing an instruction to start. The opening-closing unit 32 may be automatically started at the designated date and time according to the schedule set by a worker. Further, the opening-closing unit 32 opens the control valves 6 positioned at opposite ends of the flow section where refrigerant leakage is not detected by the first detection unit 34. Note that the opening-closing unit 32 does not open the control valve 6 positioned between the flow section where refrigerant leakage is not detected and the flow section where refrigerant leakage is detected.

First Comparison Unit 33

The first comparison unit 33 compares a pressure of refrigerant to a predetermined threshold. The pressure of refrigerant is measured by the indoor-side pressure sensor 21, assigned with a sensor count equal to the target count, in the flow section in which the control valves 6 closed by the opening-closing unit 32 are positioned at opposite ends. The target count is a serial number representing a target indoor-side pressure sensor 21 on which the controller 9 performs processing.

First Detection Unit 34

The first detection unit 34 detects refrigerant leaking in the flow section where the pressure of refrigerant measured by the indoor-side pressure sensor 21 is determined to be lower than the predetermined threshold by the first comparison unit 33.

The controllers 9 accommodated in the respective control boxes 5 cooperate with each other by communicating with each other to identify the flow section where refrigerant leaks. Further, the controllers 9 accommodated in the respective control boxes 5 cooperate with each other by communicating with each other in such a manner as to maintain the control valves 6 in a closed state, which are positioned at opposite ends of the flow section where refrigerant leakage is detected, and as to open the control valves 6 positioned at opposite ends of the flow section where refrigerant leakage is not detected, Note that the controllers 9 may display the location where refrigerant leaks or display information that the indoor units 2 stop operating on a remote control (not illustrated) included in the indoor units 2, a centralized controller (not illustrated) connected to the outdoor unit 3, or other controller.

FIG. 4 is a flowchart illustrating the operation of the controller 9 according to Embodiment 1. With reference to FIG. 4 , the procedure for detecting the location of refrigerant leakage by the controller 9 a is now described. First, when the refrigerant leakage detection sensor 7 a detects refrigerant leakage, the opening-closing unit 32 in the controller 9 a doses the indoor-side pipe control valves 41 a and the outdoor-side pipe control valve 42 a (step S1). The opening-closing unit 32 in the controller 9 a closes the indoor-unit control valves 12 a (step S2). Further, the opening-closing unit 32 communicates with the controller 9 b to instruct the controller 9 b to close the outdoor-side pipe control valve 42 b accommodated in the control box 5 b (step S3).

Next, the first comparison unit 33 determines whether the target count exceeds the last sensor count assigned to the indoor-side pressure sensor 21 a (step S4). When the target count does not exceed the last sensor count (NO in step S4), the first comparison unit 33 determines whether the pressure, detected by the indoor-side pressure sensor 21 a assigned with a sensor count equal to the target count, is lower than the threshold (step S5). The pressure of refrigerant measured by the indoor-side pressure sensor 21 a is higher than the threshold (NO in step S5), the opening-closing unit 32 opens the indoor-unit control valve 12 a and the indoor-side pipe control valve 41 a that are positioned at opposite ends of the flow section in which the indoor-side pressure sensor 21 a is provided (step S6). The controller 9 a communicates with the controller 9 b to inform that there is no influence of refrigerant (step S7). Upon receiving the communication, the controller 9 b performs operation to detect the location of refrigerant leakage. As described above, in a case where a plurality of controllers 9 are provided, all the controllers 9 detect the location of refrigerant leakage.

The pressure of refrigerant measured by the indoor-side pressure sensor 21 a is lower than the threshold (YES in step S5), the first detection unit 34 detects refrigerant leakage in the flow section where the indoor-side pressure sensor 21 a is provided (step S8). Further, the controller 9 a maintains the indoor-unit control valve 12 a and the indoor-side pipe control valve 41 a in a closed state, which are positioned at opposite ends of the flow section where refrigerant leakage is detected (step S9). Then, the controller 9 a increments the target count (step S10).

When the target count exceeds the last sensor count assigned to the indoor-side pressure sensor 21 a (YES in step S4), the controller 9 a determines whether any of the indoor-side pipe control valves 41 a is opened (step S11). When at least one of the indoor-side pipe control valves 41 a is opened (YES in step S11), the opening-closing unit 32 opens the outdoor-side pipe control valve 42 a (step S12). When any of the indoor-side pipe control valves 41 a is not opened (NO in step S11), the controller 9 a does not change the current opened or closed state of the indoor-side pipe control valves 41 a or the outdoor-side pipe control valve 42 a. Thereafter, the controller 9 a communicates with the outdoor unit 3 and the control box 5 b to inform that detection of the location of refrigerant leakage has ended (step S13).

According to Embodiment 1, the controller 9 compares the pressure of refrigerant measured by each of the indoor-side pressure sensors 21 to a predetermined threshold in the flow section in which the indoor-unit control valve 12 and the indoor-side pipe control valve 41 are positioned at opposite ends. In general, when refrigerant leaks from a refrigerant pipe, the pressure of refrigerant flowing through the refrigerant pipe decreases. As described above, the controller 9 compares the pressure of refrigerant measured by the indoor-side pressure sensor 21 to the predetermined threshold. Due to this operation, the controller 9 detects refrigerant leaking in the flow section where the pressure of refrigerant measured by the indoor-side pressure sensor 21 is determined to be lower than the predetermined threshold. Therefore, the air-conditioning system 1 can locate where refrigerant leaks in the refrigerant pipe 4.

According to Embodiment 1, the controller 9 opens the control valves 6 positioned at opposite ends of the flow section where refrigerant leakage is not detected. Thus, refrigerant flows through the flow section of the refrigerant pipe 4 where refrigerant does not leak. Therefore, the air-conditioning system 1 can continue running by using the refrigerant pipe 4 excluding the flow section where refrigerant leaks.

Further, according to Embodiment 1, the air-conditioning system 1 includes the control boxes 5. In the control boxes 5, the branch portions 11, the pipe control valves 13, and the controllers 9 are accommodated. In general, in a case where the air-conditioning system 1 is installed in a building or other space, management of the pipe control valves 13 and the controllers 9 is complicated. As described in Embodiment 1, the branch portions 11 the pipe control valves 13, and the controllers 9 are accommodated in the corresponding control boxes 5, so that the branch portions 11 the control valves 6, and the controllers 9 are managed based on each control box 5. Therefore, the air-conditioning system 1 improves the ease of maintenance, and can immediately deal with refrigerant leakage to thereby minimize the influence of refrigerant leakage.

According to Embodiment 1, when the refrigerant leakage detection sensor 7 detects refrigerant leaking from the refrigerant pipe 4, the pressure sensor 8 measures the pressure of refrigerant. Due to this operation, the air-conditioning system 1 can immediately locate where refrigerant leaks in the refrigerant pipe 4. Therefore, the air-conditioning system 1 can immediately deal with the refrigerant leakage to thereby minimize the influence of refrigerant leakage.

Further, according to Embodiment 1, the controller 9 maintains the control valves 6 in a closed state, which are positioned at opposite ends of the flow section where refrigerant leakage is detected. This prevents refrigerant from flowing to the flow section where refrigerant leakage is detected. Therefore, further refrigerant leakage can be prevented after the control valves 6 are closed.

When one of the controllers 9 receives communication from the other of the controllers 9, the one of the controllers 9 controls a plurality of the control valves 6 connected to the one of the controllers 9. Thus, a plurality of controllers 9 cooperating with each other by communicating with each other make a comparison of the pressure of refrigerant in the flow sections to the threshold in turn. Therefore, the air-conditioning system 1 can efficiently locate where refrigerant leaks in the refrigerant pipe 4 in its entirety.

According to Embodiment 1, the controller 9 may set a predetermined time interval at which the pressure sensor 8 measures the pressure of refrigerant. Due to this operation, the air-conditioning system 1 can automatically perform regular maintenance. Therefore, the air-conditioning system 1 can reduce the maintenance load. For example, in a case where the air-conditioning system 1 uses refrigerant with a high level of safety such as a flammable refrigerant, the air-conditioning system 1 can omit the refrigerant leakage detection sensor 7. In this case, the air-conditioning system 1 can reduce the number of facilities needed, and can improve the design flexibility.

Embodiment 2

FIG. 5 is a circuit diagram illustrating an air-conditioning system 101 according to Embodiment 2. FIG. 6 is a functional block diagram illustrating a controller 109 according to Embodiment 2. The present Embodiment 2 is different from Embodiment 1 in that the outdoor unit 3 is provided with an outdoor-unit control valve 14. In the present Embodiment 2, the same components as those in Embodiment 1 are denoted by the same reference signs, and thus descriptions thereof are omitted. The differences from Embodiment 1 are mainly described below.

Outdoor-Unit Control Valve 14 and Outdoor-Side Pressure Sensor 22

As illustrated in FIG. 5 , the control valve 6 includes the outdoor-unit control valve 14. The outdoor-unit control valve 14 is provided in the outdoor unit 3 to control a flow of refrigerant. An outdoor-side pressure sensor 22 is provided between the outdoor-unit control valve 14 and the outdoor-side pipe control valve 42 to measure the pressure of refrigerant flowing through the refrigerant pipe 4.

Controller 109

As illustrated in FIG. 6 , the controller 109 includes a second comparison unit 133, and a second detection unit 134. The second comparison unit 133 and the second detection unit 134 are made up of algorithms.

Second Comparison Unit 133

The second comparison unit 133 compares the pressure of refrigerant measured by the outdoor-side pressure sensor 22 to a predetermined threshold in a plurality of flow sections dosed by the opening-closing unit 32.

Second Detection Unit 134

The second detection unit 134 detects refrigerant leaking in the flow section where the pressure of refrigerant measured by the outdoor-side pressure sensor 22 is determined to be lower than the predetermined threshold by the comparison unit.

According to Embodiment 2, a controller 109 a compares the pressure of refrigerant measured by the outdoor-side pressure sensor 22 to a predetermined threshold in the flow section in which the outdoor-unit control valve 14 and the outdoor-side pipe control valve 42 are positioned at opposite ends. In general, when refrigerant leaks from the refrigerant pipe 4, the pressure of refrigerant flowing through the refrigerant pipe 4 decreases. As described above, the controller 109 compares the pressure of refrigerant measured by the outdoor-side pressure sensor 22 to the predetermined threshold. Due to this operation, the controller 109 detects refrigerant leaking in the flow section where the pressure of refrigerant measured by the outdoor-side pressure sensor 22 is determined to be lower than the predetermined threshold. Therefore, the air-conditioning system 101 can still detect refrigerant leaking even in the refrigerant pipe 4 connecting to the outdoor unit 3 and to the control box 5.

Embodiment 3

FIG. 7 is a circuit diagram illustrating an air-conditioning system 201 according to Embodiment 3. The present Embodiment 3 is different from Embodiment 1 in that the air-conditioning system 201 includes a backup pipe 204. In the present Embodiment 3, the same components as those in Embodiment 1 and Embodiment 2 are denoted by the same reference signs, and thus descriptions thereof are omitted.

The differences from Embodiment 1 and Embodiment 2 are mainly described below.

Refrigerant Pipe 4

As illustrated in FIG. 6 , the outdoor unit 3, the control boxes 5, and the indoor unit 2 are connected by the refrigerant pipe 4 and the backup pipe 204. The backup pipe 204 runs parallel to the refrigerant pipe 4, and is used when refrigerant leakage has occurred in the refrigerant pipe 4. The backup pipe 204 is provided at a location where, for example, breakage of or other damage to a pipe is more likely to occur due to the influence exerted on the pipe by the surrounding environment such as vibrations or chemical substances.

According to Embodiment 3, the air-conditioning system 201 includes the backup pipe 204. When refrigerant leakage has occurred in a portion of the refrigerant pipe 4, and thus a flow of the refrigerant is restricted, then the air-conditioning system 201 controls the flow of the refrigerant such that the refrigerant flows through the backup pipe 204 running parallel to the refrigerant pipe 4. Therefore, even when refrigerant leaks, the air-conditioning system 201 can still allow all the indoor units 2 to continue running. While the air-conditioning system 201 continues running, a worker can still repair the pipe.

REFERENCE SIGNS LIST

1: air-conditioning system, 2, 2 a, 2 b, 2 c: indoor unit, 3: outdoor unit, 4: refrigerant pipe, 5, 5 a, 5 b, 5 c: control box, 6: control valve, 7, 7 a, 7 b, 7 c: refrigerant leakage detection sensor, 8, 8 a, 8 b, 8 c: pressure sensor, 9, 9 a, 9 b, 9 c: controller, 11, 11 a, 11 b, 11 c: branch portion, 12, 12 a, 12 b, 12 c: indoor-unit control valve, 13, 13 a, 13 b, 13 c: pipe control valve, 14: outdoor-unit control valve, 21, 21 a, 21 b, 21 c: indoor-side pressure sensor, 22: outdoor-side pressure sensor, 31: communication line, 32: opening-closing unit, 33: first comparison unit, 34: first detection unit, 41, 41 a, 41 b, 41 c: indoor-side pipe control valve, 42, 42 a, 42 b, 42 c: outdoor-side pipe control valve, 101: air-conditioning system, 109: controller, 133: second comparison unit, 134: second detection unit, 204: backup pipe 

1. An air-conditioning system comprising: a plurality of indoor units configured to condition air in a room; an outdoor unit configured to supply refrigerant to each of the indoor units; a refrigerant pipe including a branch portion from which the refrigerant pipe branches off in parallel for each of the indoor units, the refrigerant pipe connecting each of the indoor units and the outdoor unit through the branch portion, the refrigerant pipe being divided into a plurality of flow sections, the refrigerant pipe being a pipe through which refrigerant flows; a plurality of control valves provided in the refrigerant pipe such that the plurality of control valves are positioned at opposite ends of each of the flow sections, the plurality of control valves being configured to control a flow of refrigerant in the flow sections; a plurality of pressure sensors provided on the refrigerant pipe, and configured to measure a pressure of refrigerant flowing through the refrigerant pipe; and a controller connected to a plurality of the control valves, and configured to control a plurality of the control valves, wherein the control valves include indoor-unit control valves provided in a plurality of the indoor units, and a plurality of pipe control valves provided in the refrigerant pipe, the pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units, the pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves, and wherein the controller opens or closes the control valves connected to the controller, compares a pressure of refrigerant to a predetermined threshold, the pressure of refrigerant being measured by each of the indoor-side pressure sensors, in a plurality of the flow sections where the control valves closed are positioned at opposite ends, detects refrigerant leaking in the flow section where a pressure of refrigerant measured by each of the indoor-side pressure sensors is determined to be lower than the predetermined threshold, and causes the pressure sensor to measure the pressure of refrigerant at a predetermined time interval so as to allow the air-conditioning system to perform regular maintenance.
 2. The air-conditioning system of claim 1, wherein the control valves further include an outdoor-unit control valve provided in the outdoor unit, the pipe control valves further include an outdoor-side pipe control valve provided between the branch portion and the outdoor unit, the pressure sensors further include an outdoor-side pressure sensor connected to the controller and provided between the outdoor-unit control valve and the outdoor-side pipe control valve, and wherein the controller compares a pressure of refrigerant to a predetermined threshold, the pressure of refrigerant being measured by the outdoor-side pressure sensor, in the flow sections where the control valves closed are positioned at opposite ends, and detects refrigerant leaking in the flow section where a pressure of refrigerant measured by the outdoor-side pressure sensor is determined to be lower than the predetermined threshold.
 3. The air-conditioning system of claim 1, wherein the controller opens the control valves positioned at opposite ends of the flow sections where refrigerant leakage is not detected.
 4. (canceled)
 5. The air-conditioning system of claim 1, further comprising a backup pipe that is a spare pipe running parallel to the refrigerant pipe, and configured to connect the indoor units and the outdoor unit.
 6. (canceled)
 7. The air-conditioning system of claim 1, further comprising a refrigerant leakage detection sensor configured to detect refrigerant leaking from the refrigerant pipe, wherein when the refrigerant leakage detection sensor detects refrigerant leaking from the refrigerant pipe, the pressure sensors measure a pressure of refrigerant.
 8. The air-conditioning system of claim 1, wherein the controller maintains the control valves in a closed state, the control valves being positioned at opposite ends of the flow section where refrigerant leakage is detected.
 9. An air-conditioning system comprising: a plurality of indoor units configured to condition air in a room; an outdoor unit configured to supply refrigerant to each of the indoor units; a refrigerant pipe including a branch portion from which the refrigerant pipe branches off in parallel for each of the indoor units, the refrigerant pipe connecting each of the indoor units and the outdoor unit through the branch portion, the refrigerant pipe being divided into a plurality of flow sections, the refrigerant pipe being a pipe through which refrigerant flows; a plurality of control valves provided in the refrigerant pipe such that the plurality of control valves are positioned at opposite ends of each of the flow sections, the plurality of control valves being configured to control a flow of refrigerant in the flow sections; a plurality of pressure sensors provided on the refrigerant pipe, and configured to measure a pressure of refrigerant flowing through the refrigerant pipe; and a controller connected to a plurality of the control valves, and configured to control a plurality of the control valves, wherein the control valves include indoor-unit control valves provided in a plurality of the indoor units, and a plurality of pipe control valves provided in the refrigerant pipe, the pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units, the pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves, and wherein the controller opens or closes the control valves connected to the controller, compares a pressure of refrigerant to a predetermined threshold, the pressure of refrigerant being measured by each of the indoor-side pressure sensors, in a plurality of the flow sections where the control valves are positioned at opposite ends, detects refrigerant leaking in the flow section where a pressure of refrigerant measured by each of the indoor-side pressure sensors is determined to be lower than the predetermined threshold, wherein the controller includes a plurality of controllers, and when one of the controllers receives communication from an other of the controllers, the one of the controllers controls a plurality of the control valves connected to the one of the controllers.
 10. An air-conditioning system comprising: a plurality of indoor units configured to condition air in a room; an outdoor unit configured to supply refrigerant to each of the indoor units; a refrigerant pipe including a branch portion from which the refrigerant pipe branches off in parallel for each of the indoor units, the refrigerant pipe connecting each of the indoor units and the outdoor unit through the branch portion, the refrigerant pipe being divided into a plurality of flow sections, the refrigerant pipe being a pipe through which refrigerant flows; a plurality of control valves provided in the refrigerant pipe such that the plurality of control valves are positioned at opposite ends of each of the flow sections, the plurality of control valves being configured to control a flow of refrigerant in the flow sections; a plurality of pressure sensors provided on the refrigerant pipe, and configured to measure a pressure of refrigerant flowing through the refrigerant pipe; a controller connected to a plurality of the control valves, and configured to control a plurality of the control valves; and a control box, the control box being a container configured to accommodate therein the branch portion, the pipe control valves, and the controller, wherein the control valves include indoor-unit control valves provided in a plurality of the indoor units, and a plurality of pipe control valves provided in the refrigerant pipe, the pipe control valves include a plurality of indoor-side pipe control valves provided between the branch portion and the indoor units, the pressure sensors include a plurality of indoor-side pressure sensors connected to the controller and provided between the indoor-unit control valves and the indoor-side pipe control valves, and wherein the controller opens or closes the control valves connected to the controller, compares a pressure of refrigerant to a predetermined threshold, the pressure of refrigerant being measured by each of the indoor-side pressure sensors, in a plurality of the flow sections where the control valves are positioned at opposite ends, and detects refrigerant leaking in the flow section where a pressure of refrigerant measured by each of the indoor-side pressure sensors is determined to be lower than the predetermined threshold, 